It is proposed to study colicin-induced ion movements, continuing the present studies on colicin-induced changes in H ion/O ratios. It is proposed to study localized pH and structural changes localized in the neighborhood of the colicin using covalently binding fluorescence probes. It is proposed to document the use of changes in probe rotational relaxation time as an accurate method to determine membrane phase transitions in whole cells, and to show by similar techniques that the inner and outer membrane have different microviscosities. BIBLIOGRAPHIC REFERENCES: G. Weber, S. L. Helgerson, W.A. Cramer, and G. Mitchell (1976) "Changes in Rotational Motion of a Cell-Bound Fluorophore Caused by Colicin E1: A Study by Fluorescence Polarization and Differential Polarized Phase Fluorometry" Biochemistry, in press. S.L. Helgerson, W.A. Cramer, and D.J. Morre (1976) "Evidence for an increase in microviscosity of plasma membranes from soybean hypocotyle induced by the plant hormone, indole-3-acetic acid. Plant Physiol. in press.